Design, implementation and control of self-aligning, bowden cable-driven, series elastic exoskeletons for lower extremity rehabilitation

We present AssistOn-Leg, a modular, self-aligning exoskeleton for robotassisted rehabilitation of lower extremities. AssistOn-Leg consists of three selfaligning, powered exoskeletons targeting ankle, knee and hip joints, respectively. Each module can be used in a stand-alone manner to provide therapy to its corresponding joint or the modules can be connected together to deliver natural gait training to patients. In particular, AssistOn-Ankle targets dorsiflexion/ plantarflexion and supination/pronation of human ankle and can be configured to deliver balance/proprioception or range of motion/strengthening exercises; AssistOn-Knee targets flexion/extension movements of the knee joint, while also accommodating its translational movements in the sagittal plane; and AssistOn- Hip targets flexion/extension movements hip joint, while allowing for translations of hip-pelvis complex in the sagittal plane. Automatically aligning their joint axes, modules of AssistOn-Leg ensure an ideal match between human joint axes and the exoskeleton axes. Self-alignment of the modules not only guarantees ergonomy and comfort throughout the therapy, but also significantly shortens the setup time required to attach a patient to the exoskeleton. Bowden cable-driven series elastic actuation is utilized in the modules located at the distal (knee and ankle) joints of AssistOn-Leg to keep the apparent inertia of the system low, while simultaneously providing large actuation torques required to support human gait. Series elasticity also provides good force tracking characteristics, active back-driveability within the control bandwidth and passive compliance as well as impact resistance for excitations above this bandwidth. AssistOn-Hip is designed to be passively back-driveable with a capstan-based multi-level transmission. Thanks to passive compliance of the distal modules and passive backdriveability of the hip module, the overall design ensures safety even under power losses and robustness throughout the whole frequency spectrum

Analisa Statis dan Distribusi Kekakuan Robot Paralel 3-RPS Sebagai Alat Rehabilitasi Tumit

Proses penyembuhan atau rehabilitasi cedera tumit selama ini biasa dilakukan dengan cara tradisional. Namun tidak semua pasien dapat menerima rehabilitasi tradisional dikarenakan terapis hanya bisa melayani satu pasien secara bergantian dimana prosesnya diulang terus menerus sehingga membutuhkan jumlah tenaga yang sama dalam waktu yang lama. Efektifitas pelatihan juga sangat tergantung pada keahlian terapis. Robot paralel 3-RPS merupakan sebuah mekanisme robot yang mempunyai tiga derajat kebebasan dan masing-masing kakinya tersusun dari revolute joint, prismatic joint, dan spherical joint. Mekanisme tersebut kemudian dikembangkan dalam tugas akhir ini menjadi alat rehabilitasi tumit. Penelitian kali ini bertujuan untuk mengetahui kondisi kesetimbangan dari konfigurasi robot paralel 3-RPS berdasarkan gaya dan momen virtual pada mekanisme. Selain itu, penelitian ini bertujuan untuk mengetahui pengaruh parameter desain terhadap distribusi kekakuan pada robot paralel 3-RPS sebagai alat rehabilitasi tumit. Dalam melakukan analisa, dimulai dengan pemodelan kinematika maupun letak koordinat pada satu kaki robot untuk menentukan gaya dan momen constraint serta gaya dan momen aktuasi dalam bentuk twist dan wrench pada masing-masing joint. Gaya dan momen tersebut kemudian dirumuskan menjadi matriks Jacobian yang selanjutnya digunakan untuk menganalisa kesetimbangan statis maupun kekakuan. Matriks Jacobian dirumuskan menjadi matriks Kekakuan dan disimulasikan menggunakan perangkat lunak MATLAB sehingga didapatkan grafik yang menjelaskan hubungan antara nilai kekakuan terhadap variasi parameter desain. Hasil yang didapatkan adalah masing-masing kaki pada struktur robot paralel 3-RPS mempunyai satu gaya constraint dan satu gaya aktuasi. Kondisi kesetimbangan robot paralel 3-RPS direpresentasikan oleh matrik Jacobian yang didapat dengan menggabungkan semua gaya-gaya tersebut. Semakin jauh posisi kaki ketiga terhadap kaki pertama, maka kekakuan robot akan semakin rendah. Semakin besar ukuran platform, maka nilai kekakuan robot akan semakin besar. Untuk mendapatkan nilai kekakuan yang tinggi, posisi kaki kedua dapat divariasikan dan bergantung pada arah wrench yang diterapkan pada platform ======================================================================================================= Healing process or rehabilitation of ankle injuries during this time is usually done in the traditional way. However, not all patients can receive traditional rehabilitation because the therapist can only serve one patient in turn where the process is repeated continuously so that it takes the same amount of energy for a long time. The effectiveness of the training is also highly dependent on the therapist's expertise. The 3-RPS parallel robot is a robotic mechanism that has three degrees of freedom and each leg is composed of a revolute joint, prismatic joint, and spherical joint. The mechanism is then developed in this final task to be an ankle rehabilitation device. This study aims to determine the equilibrium condition of the 3-RPS parallel robot configuration based on the virtual force and moment on the mechanism. In addition, this study aims to determine the effect of design parameters on stiffness distribution in 3-RPS parallel robot as an ankle rehabilitation device. In the analysis, starting with kinematics modeling and the location of the coordinates on one robot leg to determine the force and moment of the constraint and the force and moment of the actuation in the form of twist and wrench on each joint. Then the forces and moments are formulated into Jacobian matrices which are then used to analyze the static equilibrium and stiffness. The Jacobian matrix is formulated into a Stiffness matrix and simulated using MATLAB program to obtain a graph which explains the relationship between the stiffness distribution to variations in design parameters. The results obtained are that each leg in a 3-RPS parallel robot structure has one constraint force and one actuation force. By combining all of these forces, a Jacobian matrix formulation representing the 3-RPS parallel equilibrium condition is obtained. The farther the third leg position against the first leg, then the robot stiffness will be lower. The larger the size of the platform, then the robot stiffness will be greater. To get a large stiffness value, the position of the second leg can be varied and depends on the direction of wrench applied to the platfor

Optimal exoskeleton design and effective human-in-the-loop control frameworks for rehabilitation robotics

Attention, since they decrease the cost of repetitive movement therapies, enable quantitative measurement of the patient progress and promise development of more e ective rehabilitation protocols. The goal of this dissertation is to provide systematic frameworks for optimal design of rehabilitation robots and e ective delivery of therapeutic exercises. The design framework is built upon identification and categorization of the design requirements, and satisfaction of them through several design stages. In particular, type selection is performed to ensure imperative design requirements of safety, ergonomy and wearability, optimal dimensional synthesis is undertaken to maximize global kinematic and dynamic performance defined over the singularity-free workspace volume, while workspace optimization is performed to utilize maximum singularity-free device workspace computed via Grassmann line theory. Then, humanin- the-loop controllers that ensure coupled stability of the human-robot system are implemented in the robot task space using appropriate error metrics. The design framework is demonstrated on a forearm-wrist exoskeleton, since forearm and wrist rotations are critical in performing activities of daily living and recovery of these joints is essential for achieving functional independence of patients. In particular, a non-symmetric 3RPS-R mechanism is selected as the underlying kinematics type and the performance improvements due to workspace and multi-criteria optimizations are experimentally characterized as 27 % larger workspace volume, 32 % higher position control bandwidth and 17 % increase in kinematic isotropy when compared to a similar device in the literature. The exoskeleton is also shown to feature high passive back-driveability and accurate sti ness rendering capability, even under open-loop impedance control. Local controllers to accommodate for each stage of rehabilitation therapies are designed for the forearm-wrist exoskeleton in SO(3): trajectory tracking controllers are designed for early stages of rehabilitation when severely injured patients are kept passive, impedance controllers are designed to render virtual tunnels implementing forbidden regions in the device workspace and allowing for haptic interactions with virtual environments, and passive contour tracking controllers are implemented to allow for rehabilitation exercises that emphasize coordination and synchronization of multi degrees-of-freedom movements, while leaving the exact timing along the desired contour to the patient. These local controllers are incorporated into a multi-lateral shared controller architecture, which allows for patients to train with online virtual dynamic tasks in collaboration with a therapist. Utilizing this control architecture not only enables the shift of control authority of each agent so that therapists can guide or evaluate movements of patients or share the control with them, but also enables the implementation of remote and group therapies, as well as remote assessments. The proposed control framework to deliver e ective robotic therapies can ensure active involvement of patients through online modification of the task parameters, while simultaneously guaranteeing their safety. In particular, utilizing passive velocity field control and extending it with a method for online generation of velocity fields for parametric curves, temporal, spatial and assistive aspects of a desired task can be seamlessly modified online, while ensuring passivity with respect to externally applied forces. Through human subject experiments, this control framework is shown to be e ective in delivering evidence-based rehabilitation therapies, providing assistance as-needed, preventing slacking behavior of patients, and delivering repetitive therapies without exact repetition. Lastly, to guide design of e ective rehabilitation treatment protocols, a set of healthy human subject experiments are conducted in order to identify underlying principles of adaptation mechanism of human motor control system. In these catch-trial based experiments, equivalent transfer functions are utilized during execution of rhythmic dynamic tasks. Statistical evidence suggests that i) force feedback is the dominant factor that guides human adaptation while performing fast rhythmic dynamic tasks rather than the visual feedback and ii) as the e ort required to perform the task increases, the rate of adaptation decreases; indicating a fundamental trade-o between task performance and level of force feedback provided

Modular and Analytical Methods for Solving Kinematics and Dynamics of Series-Parallel Hybrid Robots

While serial robots are known for their versatility in applications, larger workspace, simpler modeling and control, they have certain disadvantages like limited precision, lower stiffness and poor dynamic characteristics in general. A parallel robot can offer higher stiffness, speed, accuracy and payload capacity, at the downside of a reduced workspace and a more complex geometry that needs careful analysis and control. To bring the best of the two worlds, parallel submechanism modules can be connected in series to achieve a series-parallel hybrid robot with better dynamic characteristics and larger workspace. Such a design philosophy is being used in several robots not only at DFKI (for e.g., Mantis, Charlie, Recupera Exoskeleton, RH5 humanoid etc.) but also around the world, for e.g. Lola (TUM), Valkyrie (NASA), THOR (Virginia Tech.) etc.These robots inherit the complexity of both serial and parallel architectures. Hence, solving their kinematics and dynamics is challenging because they are subjected to additional geometric loop closure constraints. Most approaches in multi-body dynamics adopt numerical resolution of these constraints for the sake of generality but may suffer from inaccuracy and performance issues. They also do not exploit the modularity in robot design. Further, closed loop systems can have variable mobility, different assembly modes and can impose redundant constraints on the equations of motion which deteriorates the quality of many multi-body dynamics solvers. Very often only a local view to the system behavior is possible. Hence, it is interesting for geometers or kinematics researchers, to study the analytical solutions to geometric problems associated with a specific type of parallel mechanism and their importance over numerical solutions is irrefutable. Techniques such as screw theory, computational algebraic geometry, elimination and continuation methods are popular in this domain. But this domain specific knowledge is often underrepresented in the design of model based kinematics and dynamics software frameworks. The contributions of this thesis are two-fold. Firstly, a rigorous and comprehensive kinematic analysis is performed for the novel parallel mechanisms invented recently at DFKI-RIC such as RH5 ankle mechanism and Active Ankle using approaches from computational algebraic geometry and screw theory. Secondly, the general idea of a modular software framework called Hybrid Robot Dynamics (HyRoDyn) is presented which can be used to solve the geometry, kinematics and dynamics of series-parallel hybrid robotic systems with the help of a software database which stores the analytical solutions for parallel submechanism modules in a configurable and unit testable manner. HyRoDyn approach is suitable for both high fidelity simulations and real-time control of complex series-parallel hybrid robots. The results from this thesis has been applied to two robotic systems namely Recupera-Reha exoskeleton and RH5 humanoid. The aim of this software tool is to assist both designers and control engineers in developing complex robotic systems of the future. Efficient kinematic and dynamic modeling can lead to more compliant behavior, better whole body control, walking and manipulating capabilities etc. which are highly desired in the present day and future robotic applications

Proceedings of the ECCOMAS Thematic Conference on Multibody Dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: ● Formulations and Numerical Methods ● Efficient Methods and Real-Time Applications ● Flexible Multibody Dynamics ● Contact Dynamics and Constraints ● Multiphysics and Coupled Problems ● Control and Optimization ● Software Development and Computer Technology ● Aerospace and Maritime Applications ● Biomechanics ● Railroad Vehicle Dynamics ● Road Vehicle Dynamics ● Robotics ● Benchmark ProblemsPostprint (published version

Multibody dynamics 2015

This volume contains the full papers accepted for presentation at the ECCOMAS Thematic Conference on Multibody Dynamics 2015 held in the Barcelona School of Industrial Engineering, Universitat Politècnica de Catalunya, on June 29 - July 2, 2015. The ECCOMAS Thematic Conference on Multibody Dynamics is an international meeting held once every two years in a European country. Continuing the very successful series of past conferences that have been organized in Lisbon (2003), Madrid (2005), Milan (2007), Warsaw (2009), Brussels (2011) and Zagreb (2013); this edition will once again serve as a meeting point for the international researchers, scientists and experts from academia, research laboratories and industry working in the area of multibody dynamics. Applications are related to many fields of contemporary engineering, such as vehicle and railway systems, aeronautical and space vehicles, robotic manipulators, mechatronic and autonomous systems, smart structures, biomechanical systems and nanotechnologies. The topics of the conference include, but are not restricted to: Formulations and Numerical Methods, Efficient Methods and Real-Time Applications, Flexible Multibody Dynamics, Contact Dynamics and Constraints, Multiphysics and Coupled Problems, Control and Optimization, Software Development and Computer Technology, Aerospace and Maritime Applications, Biomechanics, Railroad Vehicle Dynamics, Road Vehicle Dynamics, Robotics, Benchmark Problems. The conference is organized by the Department of Mechanical Engineering of the Universitat Politècnica de Catalunya (UPC) in Barcelona. The organizers would like to thank the authors for submitting their contributions, the keynote lecturers for accepting the invitation and for the quality of their talks, the awards and scientific committees for their support to the organization of the conference, and finally the topic organizers for reviewing all extended abstracts and selecting the awards nominees.Postprint (published version

Annals of Scientific Society for Assembly, Handling and Industrial Robotics 2021

This Open Access proceedings presents a good overview of the current research landscape of assembly, handling and industrial robotics. The objective of MHI Colloquium is the successful networking at both academic and management level. Thereby, the colloquium focuses an academic exchange at a high level in order to distribute the obtained research results, to determine synergy effects and trends, to connect the actors in person and in conclusion, to strengthen the research field as well as the MHI community. In addition, there is the possibility to become acquatined with the organizing institute. Primary audience is formed by members of the scientific society for assembly, handling and industrial robotics (WGMHI)

Annals of Scientific Society for Assembly, Handling and Industrial Robotics 2021

This Open Access proceedings presents a good overview of the current research landscape of assembly, handling and industrial robotics. The objective of MHI Colloquium is the successful networking at both academic and management level. Thereby, the colloquium focuses an academic exchange at a high level in order to distribute the obtained research results, to determine synergy effects and trends, to connect the actors in person and in conclusion, to strengthen the research field as well as the MHI community. In addition, there is the possibility to become acquatined with the organizing institute. Primary audience is formed by members of the scientific society for assembly, handling and industrial robotics (WGMHI)